The primary objectives are: a) The characterization of conjugates of alpha-amanitin derivatives covalently linked to the free carboxyl or free amino groups of bovine serum albumin, Concanavalin A. and rabbit immunoglobulin G with respect to moles of amanitin bound per mole of protein, effects of conjugation on conformation of amanitin and protein carrier, and in vitro inhibition of calf thymus RNA polymerose II. b) The evaluation of the toxicity of these conjugates toward AV3 (human amnion), CHO (chinese hamster ovary) and EL4 (mouse lymphocytic leukemia) cell lines. Inhibition of cell proliferation, DNA synthesis, and RNA synthesis will be determined. c) The determination of the fate of the amanitin moiety of 3H labeled amanitin-conjugates after exposure to cells. d) The evaluation of the carbohydrate binding potential of amanitin-Con A conjugates and a study of these conjugates with respect to their toxicity toward normal 3T3 and SV-40 transformed 3T3 cells. e) The determination of the potential of amanitin conjugates of immunoglobulin G directed against specific haptens to retain their ability to specifically bind the hapten, and f) The preparation of conjugates of amanitin and immunoglobulin G directed against specific cell surface proteins of cell lines AV3, CHO and EL4 followed by an evaluation of the specific toxicity of these conjugates toward each cell type.